For years, healthcare providers have been puzzled by an increase in colorectal cancer cases in young people. Now, new research suggests the culprit may be more common than most people realize. A recent study linked ultra-processed foods to increased colon cancer risk in women.
These foods make up 70% of the U.S. food supply and may be driving colon cancer rates in people under the age of 50, per the JAMA Oncology study.
For the study, researchers analyzed the diets of more than 29,000 female nurses under 50 years old. They found that those who had the highest levels of ultra-processed foods (about 10 servings a day) had a 45% higher risk of developing precancerous colon polyps than those with the lowest levels (about 3 servings a day). Those polyps may be removed if they’re detected early. But if they’re not, they may grow and turn into cancer, the researchers point out.
Meet the experts: Tiago Biachi, M.D., Ph.D., a medical oncologist in the Gastrointestinal Oncology Department at Moffitt Cancer Center; Tracey Childs, M.D., colon and rectal surgeon, chief of surgery at Providence Saint John’s Health Center, and adjunct associate professor of surgery at Saint John’s Cancer Institute in Santa Monica, CA.
“Results of this study suggest that reducing ultra-processed food intake may be an effective dietary strategy to prevent early-onset colorectal tumorigenesis,” the researchers wrote in the conclusion.
The results don’t definitively conclude that ultra-processed foods are fueling the risk of colorectal cancer cases in young people, but they do raise some questions. Here’s what oncologists want you to know.
What are ultra-processed foods?
Foods are divided into different levels of processing based on the NOVA scale. This scale breaks them into these main categories:
- Unprocessed and minimally processed foods: These foods are in their natural state or barely altered. They include things like bananas, carrots, and milk.
- Processed culinary ingredients: These include ingredients created through minimal processing—pressing, refining, grinding, or milling. Olive oil and almond flour fall into this category.
- Processed foods: These foods have been changed from their natural state, and often have sugar, oil, salt, or other substances added. Canned fish and some cheeses are in this camp.
- Ultra-processed foods: Foods in this category contain ingredients like artificial colours and flavours, preservatives for shelf stability, and other ingredients to preserve texture. Most packaged foods are considered ultra-processed.
Why might ultra-processed foods raise the risk of colon cancer?
The researchers didn’t dive into why ultra-processed foods may raise the risk of polyps (and, eventually, colon cancer). However, there are a few theories.
Ultra-processed foods may change the intestinal microbiome, explains Tracey Childs, M.D., colon and rectal surgeon, chief of surgery at Providence Saint John’s Health Center, and adjunct associate professor of surgery at Saint John’s Cancer Institute in Santa Monica, CA. That may lead to unhealthy changes that could allow cancerous cells to grow.
These foods may also encourage inflammation in the gut, which may raise the risk of pre-cancerous changes—that can then lead to early-onset colon cancer, she says.
Tiago Biachi, M.D., Ph.D., a medical oncologist in the Gastrointestinal Oncology Department at Moffitt Cancer Center, agrees, noting that “gut microbiome disruption and chronic inflammation” are likely behind this. “The findings highlight ultra-processed foods as a modifiable risk factor in the rising incidence of early-onset colorectal cancer among younger women,” he says.
The bottom line
Dr. Childs points out that the study isn’t perfect—it relies on people recalling what they ate, which isn’t always accurate. It’s also a little general about its definition of ultra-processed foods and doesn’t dive into which types may be more linked to colon cancer risk than others, she says.
Still, Dr. Childs says that the findings aren’t shocking. “We know that processed foods aren’t good for you, and this just may be another way they’re not good for you,” she says.
Dr. Biachi points out that 20% of colorectal cancers are based on genetic risk factors—but that 80% appear to be sparked by environmental, lifestyle, microbial, and early-life exposures.
How to help prevent colon cancer
Dr. Biachi recommends people focus on eating a whole-food diet and do their best to limit ultra-processed foods to 3 or fewer servings a day. “Exercise, protect your microbiome with fermented and prebiotic foods, and use minimal antibiotics,” he says. Dr. Biachi also suggests doing your best to limit alcohol intake, get 7+ hours of sleep each night, and practice good oral hygiene.
Finally, Dr. Biachi stresses the importance of staying on top of your gut health. “Start screening [for colorectal cancer] at age 45 or earlier with family history or multiple risk factors,” he says. “Never ignore red-flag symptoms—rectal bleeding, persistent pain, anaemia, bowel changes, and weight loss.”
If you develop any of these symptoms or have overall concerns about your gut health, it’s important to see a healthcare provider for an evaluation.
